This invention relates to device and method of generating high energy, high efficiency 2097 nm laser output in a CTH:YAG flash lamp pumped resonator at room temperature with low intra-cavity energy density. The design reduces the possibility of optical damage to the components and/or operation at more than double of the output comparable to existing technology.
Flash lamp pumped CTH:YAG lasers (Yttrium aluminum garnet crystal co-doped with Chromium, Thulium and Holmium ions) are used in many medical applications. The laser beam is usually delivered through a 200-1000 micron fused silica fiber. However, the CTH:YAG laser material has design problems. It exhibits low gain and high thermal lensing making it difficult to achieve high energy/high power output.
With existing technology flash lamp pumped CTH:YAG lasers operate the 2130 nm transition and a maximum output energy of approx. 4 Joules/pulse is achieved at typical output power of approx. 40 watt.
Due to higher gain and lower absorption losses of the 2130 nm transition in flash lamp pumped CTH:YAG, at room temperature, the laser will naturally operate at 2130 nm.
Historically, the aim when designing a typical CTH:YAG laser, the focus of the designer was to optimize the efficiency of the laser. In order to achieve efficient high energy/high output power the laser are operated at 2130 nm. When operating an energy efficient 2130 nm CTH:YAG laser the intra-cavity energy density will be 7-10 times higher than the output energy. Due to the high intra-cavity energy density required to operate at this level the optical breakdown is accelerated creating a problem where the typical CTH:YAG laser system requires frequent costly repairs and maintenance. Since the CTH:YAG laser is used mainly in medical applications reliability and low maintenance cost are very important.